DESCRIPTION: Surveys conducted by municipal wastewater treatment plants across the country have concluded that anywhere from 10 percent to over 70 percent of the mercury reaching the plants comes from Dental offices. These findings, combined with increasingly stringent regulations on mercury discharges, have placed pressure on the Dental profession to reduce their discharges of mercury-bearing amalgam. In Europe, similar concerns have led to the development and marketing of devices to capture Dental amalgam. The overall objective of this multiphase SBIR project is to enhance the performance of sedimentation-type Dental amalgam separators by controlling the water chemistry within the separator. Dental wastewater contains mercury in three general forms: large particles of amalgam, fine particles of amalgam, and dissolved mercury metal or ions. Simple sedimentation traps can be effective at capturing the large particles and many of the fine particles. This often accounts for over 95 percent of the total mercury burden. However, the dissolved fraction can still exceed desirable discharge limits. At present, expensive and maintenance-intensive adsorbents are needed to achieve discharge concentrations in the low-ppb range. During Phase 1, the plan is to demonstrate the feasibility of controlling the water chemistry within a simple sedimentation device to minimize the amount of dissolved mercury. Phase 1 success would lead to optimization and field demonstrations in Phase 2. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE